[Tagging] Set taxonomy metadata during import

[bradenmacdonald]

Follows #115

"As a global staff user (instance-level super user), when importing a taxonomy, I can set metadata at the time of import"

Acceptance criteria

1. Extending the import flow developed in [Tagging] Import a Taxonomy ("Bare Bones") #115 , when users select a .json or .csv file to import, they will next see this ModalDialog:
   
2. The default name should be automatically suggested based on the filename (without extension).
3. When users click Next:
   
4. And then Next again, they'll see the "Assign to organizations" tab.
   • See Figma for details and requirements.
   • If the user chooses to skip this step and assign organizations at a later stage, the taxonomy will be listed on the “No organization” list page.
   • 
5. If the user presses Cancel at any point, they'll see this warning:
   
6. If the import succeeds, a toast should inform the user:
   
7. If import errors occur, a nicer and more clear error message will be shown to the user (compared to [Tagging] Import a Taxonomy ("Bare Bones") #115's basic error alert). (See all examples in Figma.)
   

Developer notes

• The dialog Cancel/Next buttons should just look however they look when the standard Paragon components are used, so that these components are consistent with the rest of the platform/theme. You do not need to use CSS to override the styling to exactly match the mockups.
• Screenshots above are for convenience - Figma is the most up-to-date source for mockups. The scale of UI elements seen in the screenshots above may be incorrect.
• The "Assign to organizations" dialog should be re-usable as we'll need it for story [Tagging] Assign taxonomy to organizations #117 too.

[ChrisChV]

And then Next again, they'll see the "Assign to organizations" tab

@bradenmacdonald It's missing a REST API for Assign taxonomies to organizations. I think this can be separated together with this missing APIs.

[bradenmacdonald]

OK, I created #141 for that, but maybe we can combine it with #136 as you said.

[ali-hugo]

@bradenmacdonald Just sharing an updated screenshot for point number 4...